Cure behavior of very thin epoxy resin films on steel

Abstract
FT‐IR reflection absorption spectroscopy has been used to investigate the effect of a steel surface on epoxide cure. BF3 · MEA catalyzed epoxy resin films ranging in thickness from 10 to 1000 nm are cast on low carbon automotive steel and subjected to a 100°C heat treatment. The resulting epoxide conversion and aliphatic ether formation are found to be sensitive functions of film thickness, with the thinnest films exhibiting the most conversion and ether formation. Uncatalyzed epoxy resin films (5–80 nm) were subjected to an identical analysis. Prior to receiving heat treatment, some of these very thin films (up to 10 nm) exhibit a strong aliphatic ether absorption. Upon exposing these samples to the heating regimen, a strong relationship between epoxide conversion and thickness is again apparent, with thinnest films experiencing the most conversion and ether formation.
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